Countercurrent flow plate-type heat exchanger with leak detector

ABSTRACT

A countercurrent flow plate-type heat exchanger having barrier spaces between adjoining heat exchange passage and a header conducting a heat exchange fluid other than that flowing through said passage. The barrier spaces contain a corrugated metallic fin material to impart structural continuity to the heat exchanger core and to provide the heat-conducting link between adjacent fluid-conducting passages. The various barrier spaces are placed in fluid communication with a leak detection means by way of barrier space headers.

I United States Patent m1 3,590,914

{72] Inventor Franklin I). Duncan [56] References Cited LI Cm, UNITEDSTATES PATENTS g fig 32 3 2.846,l98 sn9sa Sturges l65/70 l 3,451,4136/1969 Urie mum. l65/70 a 469 623 9/1969 Rawlinga 165/70 [73] Assign NTcomm, r La Crone, Wk. Primary Examiner-Frederick L. Matteson AssistantExaminer-Theophil W. Streule Attorneys-Arthur 0. Andersen and Carl M.Lewis ABSTRACT: A countercurrent -flow plate-type heat exchanger havingbarrier spaces between adjoining heat han d h ad d 1' t h M cwmwmm Mme-mas;thizszssziz'ssemzzamzt XCHANGER WITH LEAK DETECTOR Ch 5D" spacescontain a corrugated metallic fin material to Impan m structuralcontinuity to the heat exchanger core and to pro [52] US. 165/70, videthe heat-conducting link between adjacent fluid-conduct- 165/166 ingpasages. The various barrier spaces are placed in fluid [5 I] hit. F28!3/00 communication with a leak detection means by way of barrier [50]FieldolSearch [65/70, 166 space headers.

PATENTEDJUL BIS?! 3,590,914

FIG. I

FIG. 4 FIG. 2

INVENTOR.

FRANKLIN D. DUNCAN ATTORNEY COUNTERCURRENT FLOW PLATE-TYPE HEATEXCHANGE]! WITH LEAK DETECTOR BACKGROUND OF THE INVENTION This inventionrelates to metallic plate-type heat exchangers of brazed constructionhaving fin packing within the passages thereof for conducting heat andproviding structural continuity to the heat exchanger core. Morespecifically, this invention relates to a countercurrent flow plate-typeheat exchanger for first and second heat exchange fluids wherein it isdesired to maintain separation of the first and second heat exchangefluids despite leaking of one or both of the heat exchange fluidpassages.

Heretofore heat exchangers have been provided with barrier spaces andleak detection means. However, the known barrier and leak detectionmeans used on other types of heat exchangers are not readily applicableto countercurrent heat exchangers of the plate type.

SUMMARY OF THE INVENTION The barrier spaces provided in the heatexchanger herein disclosed have the additional function of providingstructural continuity and heat conductivity between the relatively thinbut wide heat exchange fluid passages. The instant invention isparticularly useful countercurrent flow plate-type heat exchangers.

It is thus an object of this invention to provide means for receivingheat exchange fluids which may leak from either of the heat exchangecountercurrent flow passages and for preventing such fluid from leakinginto the other of said such heat exchange passages. It is a furtherobject of this invention to prevent leaks from any of the heat exchangepassages into the headers conducting another heat exchange fluid.

It is still a further object of this invention to provide an integralbarrier system between the heat exchange passages that can beincorporated into plate-type countercurrent flow heat exchanger which isformed by furnace or bath brazing.

It is a further object of this invention to provide a barrier system fora plate-type countercurrent flow heat exchanger which system may beconnected to similar systems of other plate-type heat exchangers withina heat exchanger battery without the loss of integrity of the barriersystem.

DESCRIPTION OF THE DRAWINGS The structural means to achieve theseobjectives will be apparent from the detailed description of theinvention with the accompanying drawing in which:

FIG. 1 is a perspective of a heat exchanger incorporating the instantinvention and wherein the barrier system thereof is connected to a meansfor detecting the presence of heat exchange fluid within the barrierspaces;

FIG. 2 is a vertical section through one of the heat exchange fluidpassages taken at line 2-2 of FIG. 1;

FIG. 3 is a vertical section through another of the heat exchange fluidpassages taken at line 3-3 of FIG. 1;

FIG. 4 is a vertical section through a barrier space intermediate theheat exchange fluid passages of FIGS. 2 and 3 taken at line 4-4 ofFlG.1; and

FIG. 5 is a perspective of a portion of the heat exchanger of FIG. 1showing a portion of the corrugated metallic porous sheet material whichis disposed within the heat exchanger fluid passages and barrier spaces.

DETAIL DESCRIPTION Referring now to the drawings it will be seen thatcountercurrent flow heat exchanger It) has a core 12 comprised of aplurality of metallic plate 14 of the same peripheral rectangularconfiguration and contraposed in spaced parallel relationship.

The spaces 16 between certain plates 14 are bound at the edges of plates14 by a top closing bar 18, a first side closing bar 20, a second sideclosing bar 22 and a bottom closing bar 24 as most clearly seen in FIG.2. The adjacent ends of bars 18 and 20 are spaced to define a firstfluid inlet 26 to space 16. The adjacent ends of bars 22 and 24 arespaced to define a first fluid outlet 28 from space 16. Disposed withinspace 16 adjacent each of inlet 26 and outlet 28 is a small triangularsection 30 of porous corrugated metallic sheet fin material 32 havingcrests extending vertically. Disposed laterally of each triangularsection 30 is a larger triangular section 34 of corrugated metallicsheet fin material 32 having crests extending diagonally. A largerectangular section 36 of corrugated metallic sheet fin material 32having crests extending vertically is disposed between triangularsections 34.

Disposed within the space bounded by closing bars 18, 20, 24, and 22 isan inner closing bar 38 extending along the upper edge of uppertriangular fin section 34 between the upper end of side closing bar 22and the end of top closing bar 18 adjacent inlet opening 26. Atriangular section 40 of corrugated metallic sheet fin material 32having crests extending horizontally is disposed within the space 16intermediate inner closing bar 38 and top closing bar 18. Closing bars18 and 38 are spaced at their ends adjacent the upper end of closing bar22 to provide an opening 42 communicating with the space 44 betweenclosing bars 18 and 38.

Disposed within the space bounded by closing bars 18, 20, 24, and 22 isan inner closing bar 46 extending along the lower edge of lowertriangular fin section 34 between the lower end of side closing bar 20and the end of bottom closing bar 24 adjacent outlet opening 28. Atriangular section 48 of corru gated metallic sheet fin material 32having crests extending horizontally is disposed within the space 16intermediate inner closing bar 46 and bottom closing bar 24. Closingbars 24 and 46 are spaced at their ends adjacent the lower end ofclosing bar 20 to provide an opening 50 communicating with the space 52between closing bars 24 and 46.

The spaces 17 between certain plates 14 are bound at the edges of plates14 by a top closing bar 19, a first side closing bar 21, a second sideclosing bar 23 and a bottom closing bar 25 as most clearly seen in FIG.3. The adjacent ends of bars 19 and 21 are spaced to define a secondfluid outlet 27 to space 17. The adjacent ends of bars 23 and 25 arespaced to define a second fluid inlet 29 from space 17. Disposed withinspace 17 adjacent each of outlet 27 and inlet 29 is a small triangularsection 31 of corrugated metallic sheet fin material 32 having crestsextending vertically. Disposed laterally of each triangular section 31is a larger triangular section 33 of corrugated metallic sheet finmaterial 32 having crests extending diagonally. A large rectangularsection 35 of corrugated metallic sheet fin material 32 having crestsextending vertically is disposed between triangular sections 33.

Disposed within the space bounded by closing bars 19, 21, 25, and 23 isan inner closing bar 37 extending along the upper edge of uppertriangular fin section 33 between the upper end of side closing bar 23and the end of top closing bar 19 adjacent outlet opening 27. Atriangular section 39 of corrugated metallic sheet fin material 32having crests extending horizontally is disposed within the space 17intermediate interclosing bar 37 and top closing bar 19. Closing bars 19and 37 are spaced at their ends adjacent the upper end of closing bar 23to provide an opening 41 communicating with the space 43 between closingbars 19 and 37.

Disposed within the space bounded by closing bars 19, 21, 25, and 23 isan inner closing bar 45 extending along the lower edge of lowertriangular fin section 33 between the lower end of side closing bar 21and the end of bottom closing bar 25 adjacent inlet opening 29. Atriangular section 47 of corrugated metallic sheet fin material 32having crests extending horizontally is disposed within the space 17intermediate inner closing bar 45 and bottom closing bar 25. Closingbars 25 and 45 are spaced at their ends adjacent the lower end ofclosing bar 21 to provide an opening 49 communicating with the space 51between closing bars 25 and 45.

The spaces 53 between certain plates 14 are bound at the edges of plates14 by a top closing bar 54, a first side closing bar 55, a second sideclosing bar 56, and a bottom closing bar 57, as most clearly seen inFIG. 4. The adjacent ends of closing bars 54 and 55, 54 and 56, 55 and57, and 56 and 57 are spaced to define openings 58, 59, 60, and 61respectively into space 53. Disposed adjacent each of openings 58, 59,60, and 6] is a triangular section 62 of corrugated metallic sheet finmaterial 32 having crests extending horizontally. Disposed immediatelybelow each upper pair of triangular sections 62 and immediately aboveeach pair of lower triangular sections 62 is a large triangular section63 of corrugated metallic sheet fin material 32 having crests extendingvertically. Intermediate upper fin section 63 and lower fin section 63is a large rectangular section 64 of corrugated metallic sheet finmaterial 32.

The heat exchanger It) has a first fluid inlet header 65 overlying inletopenings 26 and a first fluid outlet header 66 underlying outletopenings 28 to permit passage of a first heat exchange fluid to and fromthe core 12. Heat exchanger 10 also has a second fluid inlet header 67underlying inlet openings 29 and a second fluid outlet header 68overlying outlet openings 27. Heat exchanger 10 has a first leakdetection side header 69 overlying openings 42 and 59, a second leakdetection side header 70 overlying openings 41 and 58, a third leakdetection side header 71 overlying openings 49 and 6], and a fourth leakdetection side header 72 overlying openings 50 and 60.

The aforedescribed closing bars, sections of porous corru gated metallicfin material and headers are brazed together a an integral unit. Theclosing bars thus sealingly bridge between adjacent plates l4 while thecorrugated fin material provide structural and thermal ligamentsconnecting between adjacent plates. The corrugated fin material alsoprovides a thermal path from the spaces 16 and 17 to the adjacentplates.

Thus during operation a first heat exchange fluid is passed from header65 into inlet openings 26 through a first passage 73 including upper finsection 30, upper fin section 34, rectangular fin section 36, lower finsection 34, and lower fin section 30 from whence the first heat exchangefluid is discharged from outlet openings 28 into header 66. A secondheat exchange fluid is conducted from header 67 through inlet openings29 through a second passage 74 including lower fin section 31, lowerfill section 33, rectangular fin section 35, upper fin section 33, andupper fin section 31 from whence the second heat exchange fluid isdischarged through outlet openings 27 into outlet header 68. The firstand second heat exchange passages are separated by a space 53. However,heat is exchanged between the first and second passages via a pathincluding rectangular fin section 36, a first of plates [4, arectangular section 64, a second of plates [4, and rectangular section35.

Spaces 43, 44, and 52 are substantially inactive areas isolated from thepaths of the heat exchange fluids through the heat exchanger innerclosing bars 37, 38, 45, and 46 respectively. Since these areas are notwithin the direct flow path between the inlet and outlet of theirrespective passage, it is difficult to remove residual brazing flux fromthese areas. Residual brazing flux in certain types of heat exchangerssuch as those constructed of aluminum, can cause sufficient corro sionso that the heat exchanger may develop leaks between the passages aftera period of use. These leak passages, whatever their cause, may extendthrough the plates l4 or simply around a closing bar such as 18, 24, 19,or 25; to a header such as 68, 67, 65, or 66 respectfully.

In order to detect any interpassage leaks, that is leaks between thefirst passage 73 and the second passage 74, the heat exchanger isprovided with a complete interpassage leak barrier system. Thus it willbe apparent from the structure herein disclosed that the interpassagespaces 53 are in fluid communication with the spaces 44 via header 69,with the spaces 43 via header 70, with the spaces 52 via header 72, andwith the spaces 5] via header 71. Conversely, all of the spaces barrier43, 4, 51, and 52 are in fluid communication with barrier space 53 whichin turn is in fluid communication with conduit 75 via header 7t.

Thus either of the heat exchange fluids which might leak into thebarrier spaces is conducted through conduit 75 and pumped by pump 76 toa vessel 77 provided with a float switch 78. As the leaking fluid fillsthe vessel, float switch 78 is closed to energize an electric circuitincluding in series a potential source 79 an indicator light 80 and aswitch 78. Leaking of either of the heat exchange fluids into the otherof the heat exchange fluids is prevented and internal leaking from oneof the passages will be indicated by light 80.

While I have disclosed only a simple leak-sensing means, it should beappreciated that the pump 76, vessel 77, float switch 78 and circuitincluding potential source 79 and light 80 may be replaced by any devicecapable of sensing the presence of one or both of the particular heatexchange fluids being conducted through heat exchanger 10.

In the alternative it will be appreciated that a fluid under higherpressure than either of the heat exchange fluids may be maintained inthe barrier spaces. Leakage of this barrier space fluid into either ofthe heat exchange fluids may be detected by conventional means.

Having thus described one preferred embodiment of my invention, I claim:

I. A platetype countercurrent flow heat exchanger comprising a pluralityof metallic generally rectangular plates of similar peripheralconfiguration contraposed in substantially parallel spaced relationshipthereby defining a plurality of spatial layers therebetween; firstsealing means sealingly bridging between and extending along the marginsof a first pair of ad jacent plates to thereby define a first passagefor a first heat exchange fluid in a first of said spatial layers;second sealing means sealingly bridging between and extending along themargins of a second pair of adjacent plates to thereby define a secondpassage for a second heat exchange fluid in a second of said spatiallayers; means defining an inlet to said first passage an an outlet fromsaid second passage at one end of said heat exchanger; means defining anoutlet from said first passage and an inlet to said second passage atthe other end of said heat exchanger; a third of said spatial layersbeing disposed intermediate said first and second pairs of plates tothereby define a barrier space between said first and second passages; aplurality of heat-transmitting metallic ligaments extending through saidbarrier space and each brazed to one plate of each of said first andsecond pairs of plates; and means for detecting the passing of a fluidbetween at least one of said first and second passages and said barrierspace.

2. The apparatus as defined by claim 1 wherein said liga ments are thespans between the crests and valleys of a corru gated metallic sheet.

3. A plate-type countercurrent heat exchanger comprising a plurality ofmetallic generally rectangular plates of similar peripheralconfiguration contraposed in substantially parallel spaced relationshipthereby defining a plurality of spatial layers therebetween, firstsealing means sealingly bridging between and extending along the marginsof a first pair of ad jacent plates to thereby define a first passage ina first of said spatial layers; second sealing means sealingly bridgingbetween and extending along the margins of a second pair of adjacentplates to thereby define a second passage in a second of said spatiallayers; means defining an inlet to said first passage and an outlet fromsaid second passage at one end of said heat exchanger; means defining anoutlet from said first passage and an inlet to said second passage atthe other end of said heat exchanger; a header, the interior of which isin fluid communication with one of said inlet and outlet of said firstpassage and in fluid communication with said second sealing meansexternally of said second passage; third sealing means sealinglybridging between the plates of said second pair of plates from a pointon said second sealing means at one side of said header to another pointon said second sealing means at the other side of said header to therebydefine a barrier space in said second spatial layer between said secondpassage and said header.

4. The apparatus as defined by claim 3 including means for detecting thepassing of a fluid between at least one of said first and secondpassages and said barrier space.

5. The apparatus as defined by claim 3 wherein a third of said spatiallayers is disposed intermediate said first and second pairs of plates tothereby define a second barrier space between said first and secondspatial layers.

6. The apparatus as defined by claim 5 including a header in fluidcommunication with said first and second barrier spaces.

7. The apparatus as defined by claim 6 including means for detecting thepassing of a fluid between at least one of said first and secondpassages and said first and second spaces.

8. Aplate-type countercurrent flow heat exchanger comprising a pluralityof metallic generally rectangular plates of similar peripheralconfiguration contraposed in a substantially parallel spacedrelationship thereby defining a plurality of spatial layerstherebetween; a first series of closing bars sealingly bridging betweenand extending along the margins of a first pair of adjacent plates tothereby define a first passage in a first of said spacial layers; asecond series of closing bars sealingly bridging between and extendingalong the margins of a second pair of adjacent plates to thereby definea second passage in a second of said spacial layers; the ends of saidclosing bars of said first series being spaced to define an inlet and anoutlet for said first passage; the ends of said closing bars of saidsecond series being spaced to define an inlet and an outlet for saidsecond passage; said first passage inlet and said second pasage outletbeing adjacent and disposed at one end of said heat exchanger and saidfirst passage outlet and said second passage inlet being adjacent anddisposed at the other end of said heat exchanger whereby the relativeflow between the fluids in said first and second passages iscountercurrent; a header, the interior of which is in fluidcommunication with one of said inlet and outlet of said first passageand in fluid communication with a side of said second series of closingbars externally of said second passage; an inner closing bar sealinglybridging between the plates of said second pair of adjacent plates froma point on said second series of closing bars at one side of said headerto another point on said second series of closing bars at the other sideof said header to thereby define a barrier spaced in said second spaciallayer between said second passage and said header.

9. The apparatus as defined in claim 8 wherein one end of said innerclosing bar and one end of the closing bar of said second seriesunderlying said header are spaced to provide an opening to said barrierspace.

10. The apparatus as defined by claim 8 including fin packing withinsaid barrier space intermediate said header and said inner closing bar.

2. The apparatus as defIned by claim 1 wherein said ligaments are thespans between the crests and valleys of a corrugated metallic sheet. 3.A plate-type countercurrent heat exchanger comprising a plurality ofmetallic generally rectangular plates of similar peripheralconfiguration contraposed in substantially parallel spaced relationshipthereby defining a plurality of spatial layers therebetween, firstsealing means sealingly bridging between and extending along the marginsof a first pair of adjacent plates to thereby define a first passage ina first of said spatial layers; second sealing means sealingly bridgingbetween and extending along the margins of a second pair of adjacentplates to thereby define a second passage in a second of said spatiallayers; means defining an inlet to said first passage and an outlet fromsaid second passage at one end of said heat exchanger; means defining anoutlet from said first passage and an inlet to said second passage atthe other end of said heat exchanger; a header, the interior of which isin fluid communication with one of said inlet and outlet of said firstpassage and in fluid communication with said second sealing meansexternally of said second passage; third sealing means sealinglybridging between the plates of said second pair of plates from a pointon said second sealing means at one side of said header to another pointon said second sealing means at the other side of said header to therebydefine a barrier space in said second spatial layer between said secondpassage and said header.
 4. The apparatus as defined by claim 3including means for detecting the passing of a fluid between at leastone of said first and second passages and said barrier space.
 5. Theapparatus as defined by claim 3 wherein a third of said spatial layersis disposed intermediate said first and second pairs of plates tothereby define a second barrier space between said first and secondspatial layers.
 6. The apparatus as defined by claim 5 including aheader in fluid communication with said first and second barrier spaces.7. The apparatus as defined by claim 6 including means for detecting thepassing of a fluid between at least one of said first and secondpassages and said first and second spaces.
 8. A plate-typecountercurrent flow heat exchanger comprising a plurality of metallicgenerally rectangular plates of similar peripheral configurationcontraposed in a substantially parallel spaced relationship therebydefining a plurality of spatial layers therebetween; a first series ofclosing bars sealingly bridging between and extending along the marginsof a first pair of adjacent plates to thereby define a first passage ina first of said spacial layers; a second series of closing barssealingly bridging between and extending along the margins of a secondpair of adjacent plates to thereby define a second passage in a secondof said spacial layers; the ends of said closing bars of said firstseries being spaced to define an inlet and an outlet for said firstpassage; the ends of said closing bars of said second series beingspaced to define an inlet and an outlet for said second passage; saidfirst passage inlet and said second passage outlet being adjacent anddisposed at one end of said heat exchanger and said first passage outletand said second passage inlet being adjacent and disposed at the otherend of said heat exchanger whereby the relative flow between the fluidsin said first and second passages is countercurrent; a header, theinterior of which is in fluid communication with one of said inlet andoutlet of said first passage and in fluid communication with a side ofsaid second series of closing bars externally of said second passage; aninner closing bar sealingly bridging between the plates of said secondpair of adjacent plates from a point on said second series of closingbars at one side of said header to another point on said second seriesof closing bars at the other side of said header to thereby define abarrier spaced in said second spacial layer between said second passageand said header.
 9. The apparatus as defined in claim 8 wherein one endof said inner closing bar and one end of the closing bar of said secondseries underlying said header are spaced to provide an opening to saidbarrier space.
 10. The apparatus as defined by claim 8 including finpacking within said barrier space intermediate said header and saidinner closing bar.